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Unit 5: Animals & Plants. Do Now: Set up the timeline on the back of your notes, by marking one end “4,500 MYA” and the other “Present” In the “Do Now” section: How many billion is 4,500 million?. Our Final Unit.
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Unit 5: Animals & Plants Do Now: Set up the timeline on the back of your notes, by marking one end “4,500 MYA” and the other “Present” In the “Do Now” section: How many billion is 4,500 million?
Our Final Unit • Our final unit will investigate the animals, plants, and other organisms which developed after the Cambrian Explosion about 543 million years ago: • Plants • Complex animals • But First… their history as told by the fossil record.
Pre-Cambrian Earth • The Precambrian Eon begins with the formation of the solar system about 4,500 MYA (= 4.5 BYA). • The Pre-Cambrian is incomprehensibly long: it is 86% of Earth’s history. • Rocks form: 4,000 MYA • Abiogenesis (life “evolves”): 3,800 MYA • Eukaryotes evolve (endosymbiosis): 2,700 MYA • The Precambrian Eon lasts until 543 MYA, with an event commonly called the Cambrian Explosion
Pre-Cambrian Life • Prokaryotes are the only life on Earth for over a billion years. • By the end of the Precambrian Eon, some simple animals (sponges, flatworms, roundworms, cnidarians) had evolved. • A mass extinction occurs (Vendian) 543 MYA, officially ending the Precambrian Eon
Cambrian Explosion (4th box) 540 MYA • The Cambrian Explosion (or Cambrian diversification; 540 MYA) was a brief period in history where many new types of organisms evolve: • Arthropods • Chordates • Hard-Shelled animals • No major animal phyla have evolved since the Cambrian Explosion… why?
The “Cambrian” and “Paleozoic” • Cambrian refers to the first geological period within the larger Paleozoic Eon.
Later in the Paleozoic • Land Plants and Fishes Evolve: 480 MYA • Reptiles Evolve: 350 MYA • These are boxes 5 and 6…
End of the Paleozoic: the Permian Extinction • “The mother of all extinctions.” • Somewhere between 70 and 95% of all organisms become extinct 250 MYA. • Worst mass extinction ever recorded on Earth. Competing hypotheses over cause.
Mesozoic Eon = “Age of the Dinosaurs” 248 – 65 MYA • Dinosaurs and Mammals Evolve: 220 MYA (Box 7) Cretaceous Jurassic Triassic
Birds – Branch of the Dino Family Tree • Birds evolve 150 MYA (Box 8)
Cenozoic Eon: 64 MYA to Today • You are living in the Cenozoic Eon, the “Age of Mammals.” • Begins with the K-T extinction 65 million years ago (meteorite that wiped out the dinosaurs) Box 9 • Box 10: Humans diverge from ape populations 6 MYA.
THINK • Can you imagine a reason why no major animal phylum has evolved in the last 500 million years?